<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<link rel="stylesheet" type="text/css" href="./yxj.css">
		<style type="text/css">
			div{
				height: 100px;
				width: 100px;
				background: black;
			}
			
		</style>
	</head>
	<body>
		<div class="bg_blue"  id="div1" style="background:yellow"></div>
		<div class="bg_green"></div>
		<div class="bg_blue"></div>
	</body>
</html>
